component MyComponent inherits HorizontalLayout {
  height: 300px;
  width: 300px;
  Rectangle {height: 50px;width: 50px;background: red;}
  @children
  Text {
    text: "I am a Text";
  }
}

export component MainWindow inherits Window {
  width: 300px;
  height: 300px;
  
  MyComponent {
    Rectangle {height: 50px;width: 50px;background: blue;}
  }
}